Fluid pressure apparatus



F. D. SINGLETON FLUID PRESSURE APPARATUS ,Filed Nov. 3, 1939 April 21,1942.

fizz/26210. J" z'lzglefoiz INVENTOR VBY I fizewz TTORN Y Patented Apr.21, 1942 Del.

one-half to Fred C. Mitchell, Wilmington,

Application November 3, 1939, Serial No. 362,708 3 Claims. (01. 230-79)I This invention relates to improved fluid pressure apparatus and, moreparticularly to improvements in apparatus of the type containing arotor, enclosing case and sealing fluid adaptable. for

creating compression or suction.

Various proposals have been previously made of compressors, motors andthe. like in which compression or suction has been effected by movementof a rotor, having a helical or spiral blade, in a body of liquid, or bymovement of the body of liquid on orbetween the helical or spiral bladesof the rotor. r

There have been various disadvantages in the practical application ofsuch previous proposals,

however, including such difiiculties as those of: obtaining aneconomical and suflicient overall volumetric efficiency; overheating ofthe appa ratus due to friction and heat of compression; obtaininguniform suction or pressure, due to back discharges through the liquidentrained in the helical passages; maintaining the desired and correctlevel of sealing fluid, and the like. It is an object of thepresentinvention to overcome these and other disadvantages and toprovide a new and improved apparatus adaptable for f gaseous or liquidcompression or suction. v

Other objects and advantages of my invention will be apparent byreference to the following specification in'which the preferredembodiments are described;

The apparatus of my invention comprises an improved form of rotarycompressor or suction pump in which the rotor is in theform of a conicalscrew, forming a helical passage or passages with a portion of each ofits spirals submerged in a body of liquid, and eccentric within anenclosing case containing a liquid. The rotor of my invention, beingeccentric within the case and having details and agitating or drivingmeans around its outer face, carriesliquid within the case around withit as the rotor revolves. At the same time, each convolution of therotor being only partly submerged in the liquid, there is formeda pocketof air or other gas which is thus forced fromone end of the rotor to theother. Inasmuch as the rotor is in the form of a conical screw, andinasmuch as'the helical convolutions are reduced in width as theyapproach the outlet end, thecapacity of the passages become less andless and theconsequent pressure greater and greater toward the outletend of the rotor. l g

According to one ofthe features of myinvention, tliis general type ofapparatus is improved and made more efficient by constructing the heli--cal threads of therotor in a V or U shape, 1. e.l to the low pressureend) and the velocity attained with a. rounded "bottom to the helicalgroove.

have found that by use of suchconstruction the,

sealing fluid is displaced in such a way that a more effective seal isobtained'andtherefore the volumetric efiiciency isincreased,

As a furtherfeature of my invention, there; are providedpickuptubes,withinthe enclosing-casing, which carry ,a. part of, the sealing liquidthrougha heat exchange unit for removal of the heat caused by friction,and/orcompression of the gaseous fluid and thereafter return the fluidto the j enclosing casing; In returning thissealingliquid to theenclosing casing, it is first introduced into the hollow rotor, fromwhence it passes outthruports or nozzles provided for the purpose, thruthe l gaseous fluid beingcompressed, and returns to. the

main body of sealing liquid,

The parts or nozzles in the rotor are designed to breakup the sealingliquid, which passes .thru' them, into a flat spray and to direct thisspray, in].

a direction tangent to the periphery of the rotor.

and opposite to the direction of rotation. The

advantages of this feature are described in greater detail hereinafter.i

f cooling mediumthereby approximating isothermal compression of the gas;it provides a, means of absorbing one or more components of agaseous. i

I is presented to the gases being compressed a quan-W tity or series ofrelatively stationary sprays which largely prevent the frictionalrotation of the gases and thereby largely reduce leakage under the and,since in a machine of this general type there r and sealing liquid onthe one hand and the gases being compressed'on the other, and sincethejet velocity of the discharge of sealing liquid from the tangentialrotor ports or nozzles equals or:

; The removal of sealing" liquid; for 1 cooling and returning in thisway, accomplishes four definite improvements in the overall efficiencyand/or. utility of the machine, 1. e.,- it provides ,a means formaintaining a uniform controlled temperature within the machine; itprovidesia means. for com pressinggases while in intimate contact with amixture into the sealing fluid during compression;

is a relative rotating motion between the rotor exceeds the perinherialvelocity of the rotor, there rotor seal and increase volumetriceiiiciency.

that there is ordinarily a tendency for the gas to be forced backagainst the liquidseal, from onestage or convolution to another (thehigh pressure inside of said case.

by the gas results in appreciable loss of pressure in the high pressureend before this action stops. According to my invention, however, acheck valve or check valves are incorporated at the discharge end of thecompressor so that only that gas which may be entrained in the helicalpassage is able to leak back, thus producing an automatic unloading andconstant pressure action within the compressor.

As a further feature of this invention which,

together with those features previously described,

increases greatly the smoothness of operation and efficiency of therotor, I have provided an automatic means for discharging the sealingliquid upon stopping the compressor and for maintaining the correctlevel of sealing liquid during operation of the compressor. Theseautomatic features are accomplished, according to my invention, by meansof a spring-loaded diaphragmoperated, two way valve which is so placedin connection with the pick-up tubes for recirculation and cooling ofthe sealing liquid that, during normal operation of the compressor,sealing liquid is directed through cooling coils, from the internalportions of the enclosing case, and back to the As the speed and/orpressure decreases, however, the diaphragm valve is operated so as toretard or stop this flow of liquid through the cooling means andjtheliquid is forced into a storage receiver, which is in turn sopositionedas to give a head of liquid at a higher level than thatof theinterior of the enclosing case.

The'preierred details and embodiments of this invention will be madeclear by reference to the following description, when taken with theaccompanying drawing in which Figure 1 is a central sectional Viewthrough one form of my improved apparatus; Figure 2 is a cross sectionof the rotor of Figure 1-, the section being made at 11 as indicated inFigure 1; and Figure 3 is a diagrammatic sectional view showing thehelical threads and automatic valves of my invention.

Referring to Figure 1, the machine consists of a rotor [revolvingeccentrically within an outer casing 2 which in turn is mounted onbearings 3 and free to revolve. The rotor I has a continuous spiral finor fins-4 forming a conical spiral passage or passages progressivelydecreasing in pitch as the rotor increases in diameter, which entrainthe gaseous fluid to be compressed. The case 2 carries a sealing fluid5, the gaseous fluid to be compressed entering at 6 and discharging at'I.

The fins 4 which form the spiral or helical passages for entrainingfluids to be compressed are thickened at the base, where they join the,main body of the rotor, to form U shaped passages.

Referring to Figure II, which is a cross or I transverse section thrurotor I, outer case 2, and

sealing fluid 5, the normal position of the sealing'liquidsurface isshown at 8, the direction of rotation being clockwise. Since'in thisgeneral type of machine there is a relative plunging and receding motionbetween the rotor fins t and sealing liquid and since in my design thebases of these fins 4 are thickened or broadened, there is created atthe point 8 a greater than normal displacement of sealing liquid causingthe liquid surface to curve inward for ashort distance as indicated, 9.This causes a region of increased sealing liquid pressure against rotorI near this point, assisting the sealing liquid in preventing the fluidIII which is being compressed, from leaking under the rotor seal, whichaction produces an increase in the volumetric efficiency of the machine.

Aflixed to the outer periphery of fins 4 are a series of blade 33, withthe side of greatest dimension presented to the direction of rotation.These blades impartenergy to sealing fluid 5 to cause rotation of thebody of fluid in the direction of rotation of rotor I. The resultingcentrifugal force causes the sealing fluid to assume the shape of anannular ring within the outer casing 2.

Referring to Figure 1, there are enclosed within the outer casing 2 atube or tubes II in a stationary position with the open end or endsfacing the direction of rotation. Due to the kinetic energy of therotating sealing liquid 5, which is produced by centrifugal force andimpact against the open ends of the pick-up tubes II, the sealing liquidis forced thru passages I2 to a heat exchanger I3 and back thru passagesI I to a hollow annular space I5 within the rotor I. If heat exchange isnot desired, the fluid from pick-up tubes II may be directly passed, bymeans not shown, to the hollow annular space I5. A sealing ring IS withsuitable anti-friction facing I I is provided where the liquid passesfrom the stationary tubes I l to the rotor space I5. The rotation of theliquid while within the rotor space I 5 imparts additional energy whichassists in forcing the liquid thru ports I8 to nozzles I9 (Figure II)from where it is sprayed thru the fluid III which is being compressed.Figure II illustrates the tangential sprays 20 from these nozzles I9. Bythis movement of liquid the heat of compression is removed from thefluid It as it is formed, thereby producing isothermal compression whichnot only increases the overall efficiency of the machine but makes itpossible to compress gaseous fluids which have a tendency to decomposeupon increase of temperature. The heat is dissipated from heat exchangerI3 by circulating a cooling fluid thru tubes 2| and 22 or 1by any otherconvenient means of heat dissipaion.

As shown in Figure II, nozzles I9 produce a flat spray tangential to thesurface of the rotor I and backward with respect to the direction ofrotation. In this type of machine there is a rapid rotating motion ofthe surfaces of the rotor I relative to the fluid I II which is beingcompressed. The sprays 20 present a relatively stationary surfaceforming a series of bafiles to prevent the rotation of fluid I II whichis being compressed, thereby largely preventing leakage of the fluid I0under the rotor seal and increasing volumetric eii'iciency of themachine.

Again referring to Figures I and III, a check valve, or valves, 23 allowcompressed gases to escape from the rotor passage thru ports 24 butprevent a backward discharge, i. e., from the high pressure end of themachine back to lower stages of compression. Since a backward dischargedue to over-compression beyond that pressure for which it was designedwill result in a progressive expansion of the compressed gases in abackward direction and, due to the gas velocities reached, coupled witha considerable volume of gas in the high pressure end which must bedissipated before the action stops, a considerable amount of sealingliquid may be blown out thru the low pressure end of the machine and inany event a considerable loss of compressed gases is eifected. Accordingto my invention, valves 23 prevent any gases blowing back except thosewithin the rotor passages, which. do not exist in sufiicient volume tosustain a blow-back for a harmful period of time. Actually a balance oftank 21.

pressures is reached within the rotor passages to the extent that a moreor less continuous blowback occurs, the alternate compression anddecompression of gases in the rotor passages taking place rapidly,(decompression only partially) resulting in only a part of the normalamount of compression, and therefore only a part of the normal power,being used, which constitutes an automatic unloading of the machine.

As shown in Figure I a system of piping 25 i and automatic diaphragmorother pressure actuated valve 26 together with a storage tank 27 may beutilized according to my invention. A valve 26 is so adjusted andconnectedthat during normal operation the flow of sealing liquid thruthe tubes I2 is directed to a heat exchanger 13. However, when power isremoved fromthe machine and it reduced speed, there is resultant drop instatic pressure of sealing liquid, and in the valve 26 a correspondingreductionin pressure on the diaphragm 23, allowing a spring 29 to movethe valve and stop the flow of sealing liquid to the heat exchanger l3,directing it to a pipe 25 which in turn carries it to a storage tank-21In this way the major portion of the sealing liquid is removed from themachine when it is shut down and thus prevented from over- 5 or 1respectively.

A pipe 30 acts as a drain from storage tank 2! and terminates in an openend 3| inside the a conical screw, the helical convolutionson the rotorforming, between the convolutions, a U-shaped helical troughprogressively decreasing in pitch as the rotor increases in diameter, atleast one outlet from the hollow casing leading to a hollow annularspacewithin the rotor, ports leading from the hollow annular spacewithin the rotor to the U-shaped trough formed by the helicalconvolutions, a series of vanes afiixed to the outer periphery of therotor convolutions, with their side of greatest dimension presentedtothe direction of rotation, and a valve governing the outlet forcompressedfluid from the high pressure end of the rotor and adapted toallow for- F ward but toprevent backward flow of compressed fluidthrough the rotor.

2. An apparatus adapted for rotary compres+ sion comprising a freelyrevolvable hollow casing,

machine and at the low pressure end, with the opening facing against thedirection of rotation. When the machine is started and a valve 32 isopened there is a flow of sealing liquid into the case 2 which continuesuntil the inner surface of the annular ring of sealing liquid 5 reachesthe level of the tube opening 3|, at which time impact pressure of theliquid 5 against the tube opening 3| stops the flow thru tube30.

Should the surface of the sealing liquid 5 for any reason submerge thetube opening 3| to the extent that theresulting impact pressure becomesgreater than the static head pressure from the storage tank 21 therewill be a reversed flow in tube 30, returning sealing liquid to thestorage This provides an automatic means of maintaining a constant levelof sealing liquid 5 within case 2.

Blades 33 act upon sealing fluid 5 to produce movement of thisfluidwithin the outer casing 2 and in the direction of rotation of rotorI. Centrifugal forcecauses the sealing fluid 5 to assume By maintainingthis rotation of fluid containing a body of liquid, with inlet andoutlet means, a revolvable rotor Within and eccentric to the axis of thecasing and havingthe form of a conical screw, the helical convolutionson the rotor forming, between the convolutions, a U-shaped helicaltrough progressively decreasing in pitchas the rotor increases indiameter, at least one outlet within the hollow casing facing counter tothe direction of rotation of the rotor and leading to a hollow annularspace within the rotor, ports leading from the hollow annular spacewithin the rotor to corresponding nozzles affixed to the U-shaped troughformed by the helical convolutions, a series of vanes afiixed to theouter periphery of 'the rotor convolutions with their side of greatestdimension presented to the direction of rotation, and a valve governingthe outlet for compressed fluid from the high containing a body orliquid, with inlet and outlet Q means, a revolvable rotor and eccentricto the axis of the casing and having the form of pressure end of therotor and adapted to allow forward but to prevent backward flow ofcompressed fluid through the rotor.

3. An apparatus adapted for rotary compression comprising a freelyrevolvable hollow casing containing a body of liquid, with inlet andoutlet means, a hollow revolvable rotor within and eccentric to the axisof the casing and having theform; of a conical screw with helicalconvolutions on the rotor forming, between the convolutions, a U-shapedhelical trough progressively decreasing in pitch as the rotor increasesin diameter, at

least one stationary outlet within the hollow casing with an open endfacing counter to the di rection of rotation of the rotor, heat exchangemeans connected with at least one stationary.

outlet within the hollow casing and connected to a hollow annular spacewithin the rotor, a series of ports leading from the hollowannular'space Within the rotor, a series of nozzles connected to theports and afiixedto the trough formed by the U-shaped helicalconvolutions and pointing in a direction counter to vthe direction ofrotor rotation, a series of vanes aflixed to the outer periphcry of therotor convolutions with their side of greatest dimension presented tothe direction of rotation, and a check valve governing the, outlet forcompressed fluid from the high pressure end of the rotor and adapted toallow forward but to prevent backward flow of compressed fluid throughthe rotor. i

FRANCIS D. SINGLE'I'ON,

